Spraying machine

ABSTRACT

A spray machine can reciprocate a cantilevered support for a spray device with straight-line motion. The machine includes a pair of linked mechanisms, each including a rotating first shaft with a first arm fixed to it and including at the end of the arm a second rotating shaft with a second arm fixed to it. The second shafts are rotated hypocycloidally about the first shafts and swing linked ends of the second arms in a straight line. Spraying devices are movably cantilevered from the linked second arms so that they may be vertically positioned with respect to their support.

United States Patent 1191 1111 3,812,728

Lee et al. May 28, 1974 SPRAYING MACHINE 3,286,688 l1/l966 Blenman 118/2 36l93ll 11/1971 Rose [75] Inventors: Henry B. Lee, Cudahy, Cal1f.; 370388O H 1972 w I H8 323 Donald E. Orem; Paul L- wycofi amp er both of lndlanapohs Primary Examiner-Samuel Scott [73] Assignee: Ransburg Corporation, Indianapolis, Assistant Examinerwe5ley Ratliff,

[ d Attorney, Agent, or Firm-Merrill N. Johnson; Harry Filed: y 1973 E. Downer, Dav1d H. Badger [21] Appl. No.: 364,895 [57] ABSTRACT A spray machine can reciprocate a cantilevered sup- 521 US. Cl. 74/25 118/323 P0rt a spray device with The [51] Int. Cl. Fl 6h 21/16 machine includes a Pair of linked mechanisms each [58] Field of Search 1 18/323 2 74/25 including a rotating first shaft with a first arm fixed to 4 8922 it and including at the end of the arm a second rotating shaft with a second arm fixed to it. The second [56] References Cited shafts are rotated hypocycloidally about the first shafts and swing linked ends of the second arms in a straight UNITED STATES PATENTS line. Spraying devices are movably cantilevered from the linked second arms so that they may be vertically 310121443 12/1961 LjS n g s :i o?n. 7 i/89.22 postloned with respect to their Support" 3,103,890 9/1963 Griswold 74/25 6 Claims, 2 Drawing Figures SPRAYING MACHINE This invention relates to a machine to reciprocate a spraying device with straight-line motion. More particularly, the invention relates to a spraying machine which may be supported at the side of a straight-line conveyor to support and reciprocate one or more spraying devices over the conveyor back and forth along a straight line above a large surface object, such as an automobile body, passing the spraying machine on the conveyor.

Prior attempts to make spraying machines to coat large, complexly-shaped objects like automobile bodies have followed several approaches. One approach has been to design a machine that manipulates a spray gun while maintaining it normal to the surface of the object being coated and at a constant distance. Because of the complex shape of automobile bodies and the number of body styles, and because these complex shapes change from year to year, such machines must be capable of individual programming to each body style in each model year. The necessity that such machines be adaptable to these requirements renders such machines too expensive and impractical for automobile production and hence, such machines are not in general use. Another widely used approach has been to straddle the automotive conveyor with a structure on which the spray device rides during its manipulation. Such spray machines include spraying devices mounted on fixed tracks that are reciprocated transversely of the vehicle body. The structure of the track-supported spray gun supports a significant portion of its mechanism over the conveyor which must be lubricated. Further, the structure can collect overspray which can also fall onto the automobile bodies. Thus, such machines pose the hazard of lubricant and collected dirt dropping onto the automobile bodies being painted.

A more recent approach has been spray machines mounted along side the conveyor line on which the automobile bodies move. These spray machines provide a centilevered boom that reciprocates to and fro over the automobile body as it passes the spray machine. These machines have no structure permanently straddling the conveyor and less of a mechanism above the automobile bodies being painted, thus reducing the hazard of contamination of the automobile bodies being painted. In addition to providing a mechanism that does not permanently straddle the conveyor, the more recent spraying machines have another advantage in permitting a simple mechanism to vertically position the spraying device. Examples of the spraying machines using cantilevered booms are disclosed in U.S. Pat. No. 2,955,568 and U.S. Pat. No. 3,286,688 that incorporates a mechanism similar to that disclosed in Austrian Pat. No. 210,712.

The spraying machine of this invention, like those of the more recent approach, is mounted along side the conveyor line on which automobile bodies move. The spraying machine is adapted to reciprocate a spray device in substantially straight-line motion back and forth over the automobile body as it moves along the conveyor past the spraying machine.

In accordance with the invention, the spraying machine is supported by a support member that can be attached to a building structure. Two rotatable first shafts are supported by the support member, each rotatable first shaft carrying in fixed position with respect to the first shaft, a first arm and a synchronizing sprocket. A stationary sprocket is mounted on the axis of each rotatable first shaft. At the end of each first arm, a second rotatable shaft is rotatably carried, and each second shaft in turn carries in fixed position with respect to the second shaft, a second arm and a second sprocket. Two chains interconnect each of the stationary sprockets on the axis of a rotatable first shaft with the second sprocket on the associated second rotatable shaft, thus rotation of the first shafts results in hypocycloidal motion of the periphery of the second sprockets and the rotation of the second shaft and second arm in the opposite direction. The first and second arms are thus rotated simultaneously by the first and second shafts in opposite directions and the ends of the second arms can thus be reciprocated a distance equal to twice the sum of the length of the first arm and second arm. A link is movably carried at the end of the second arm to tie the second arms together. A driving chain interconnects the synchronizing sprockets on the rotatable first shafts so that the two rotatable first shafts can be rotated in synchronism. The spraying machine can be driven by a variety of inputs, either by rotation of the first shafts, or by reciprocation of either of the first arms. The driving method can be either a rotating out put of, for example, a hydraulic or electric motor, or if one of the first arms is used as a lever, a hydraulic or pneumatic cylinder can be used to drive the machine.

The spraying machine of this invention is adapted to include means to position the spraying device vertically to accommodate the contours of an automobile body while maintaining the straight-line reciprocation. A boom and means to adjust the position of the boom with respect to the spraying machine can allbe supported by the link connecting the second arms. A'spray device can thus be supported at the end of the boom and vertically positioned with respect to the spraying machine. Conveniently, the boom can be a parallelogram linkage and the means to operate the parallelogram linkage can be a hydraulic cylinder carried by the link.

There are several advantages of the spraying machine of this invention over the prior machines. This spraying machine can be adapted to provide contouring along its path of reciprocation rather than a straight-line motion. The machine requires substantially less height than prior machines. It will also accommodate various types of drive, either a continuously rotating input, or a reciprocating input and provides a greater stroke length for its size than prior machines by virtue of the unique structure and mechanism. The machine includes no close tolerance sliding members that can be affected by contamination from overspray and dirt from the spraying environment. The relative movement of the parts making up the machine is only by rotation and reliable bearings are conveniently and economically available for such relative motion. In addition, the structure has fewer interfitting parts which move with respect to one another. The machine moves more freely and is lessapt to bind. The reduction of friction and mass reduces the power required to drive the machine.

Various additional features of our invention will be apparent from the following description and from the drawings.

. FIG. 1 is a plan view of the spraying machine of our invention.

FIG. 2 is a side view of the machine in FIG. 1.

Referring now to the particular embodiment iliustrated in FIGS. 1 and 2, the spraying machine is supported by a support member shown in FlGS. 1 and 2 as a tubular frame; however, any such base can be used for the machine that provides rigid support of the two rotatable first shafts 11 and 12. Since the weight of the movable elements of the spraying machine is carried by support member 10 and by first shafts l1 and 12, the rotating bearings between shafts 1 1 and 12 and support member 10 should be selected to operate supporting this weight. Roller bearings or ball bearings are commercially available for this purpose.

A first arm 13, a stationary sprocket 14, and a synchronizing sprocket are all mounted on the axis of the rotatable first shaft 11. Likewise, a first arm 16, a stationary sprocket 17 and a synchronizing sprocket 18 are all mounted on the axis of the rotatable first shaft 12. First arm 13 and synchronizing sprocket 15 are carried in fixed position on rotatable first shaft 11,.and first arm 16 and synchronizing sprocket 18 are carried in fixed position on rotatable first shaft 12. By the term fixed position, we mean that the members or elements are so carried with respect to one another that their relative positions do not change during the operation of the machine, but fixed position includes an adjustable mounting between the members which permits the position of the members to be reoriented when the machine is at rest. Stationary sprockets l4 and 17 are fixed with respect to support member 10 and do not rotate.

Two rotatable second shafts 19 and 20 are: rotatably carried at the ends of first arms 13 and 16, rotatable second shaft 19 being carried at the end of first arm 13 and rotatable second shaft 20 being carried at the end of first arm 16. Rotatable second shaft 19 carries a second sprocket 21 and a second arm 22 in fixed position with respect to shaft 19. Rotatable second shaft 20 carries a second sprocket 23 and a second arm 24 in fixed position with respect to shaft 20.

Chains 25 and 26 interconnect the stationary sprocket and second sprocket at the ends of each of the first arms. Chain 25 interconnects stationary sprocket 14 with second sprocket 21, and chain 26 interconnects stationarysprocket 17 with second sprocket 23. Rotation of each firstshaft rotates each first arm and the second sprocketat its end about the stationary sprocket mounted on its axis. Chains 25 and 26 engage the teeth of each stationary sprocket and its respective second sprocket so that as the first shaft rotates, for example, clockwise, the second shaft is rotated counterclockwise by the chain. As the first arms 13 and 16 are thus rotated clockwise by the first shafts 11 and 12, respectively, the second arms 22 and 24 are rotated counterclockwise by second shafts l9 and 20, respectively.

A driving chain 27 interconnects synchronizing sprockets l5 and 18 carried in fixed position on rotating shafts l1 and 12. Driven sprockets 15 and 18 are selected to have an identical number of teeth, therefore, driving chain 27 forces the rotation of the two rotatable first shafts 11 and 12 to be simultaneous and identical in both angle and velocity. First arms 13 and 16 and second arms 22 and 24 are all the same length in the embodiment of FIGS. 1 and 2. Since first rotatable shafts 11 and 12 rotate identically, first arms 13 and 16 (in fixed position with respect to the rotatable first shafts) also rotate identically. I

Stationary sprockets 14 and 17 are selected to have an identical number of teeth. Second sprockets 21 and 23 carried in fixed position on second shafts 19 and 20, respectively, are also selected to contain an identical number of teeth. Chains 25 and 26 are thus identical. Since first shafts 11 and 12 move in synchronism, second shafts 19 and 20 move in synchronism, but in the opposite rotational direction. Second sprockets 21 and 23, however, are selected to have one-half the number of teeth of stationary sprockets 14 and 17. Since second sprockets 21 and 23 have onehalf the number of teeth as first sprockets 14 and 17, the second rotatable shaft is thus driven through twice the angle of rotation with respect to the first arm as the angle of rotation that the first arm is driven with respect to the machine support. The ends of the second arms 22 and 24 can thus be swung back and forth in a straight line.

With this machine, 360 rotation of both the first and second shafts is possible and the ends of the second arms may be reciprocated in a straight line through a distance twice the length of the sum of the first and second arms.

As shown in FIGS. 1 and 2, first arms 13 and 16 and second arms 22 and 24 are the same length L between the axes of the first and second shafts and between the second shaft and the axis of the connection of the second shafts and link 28. The spraying machine is capable of reciprocating link 28 over distance equal to twice the sum of the lengths of the arms, thus link 28 is reciprocated in straight-line motion by the spraying machine a distance of up to 4L.

A link 28 is movably carried at the end of second arms 22 and 24. Link 28 provides a rigid support to carry the spraying device to be reciprocated and its positioning mechanism. Shafts 19 and 20 thus carry the weight of second sprockets 21 and 23, second arms 22 and 24, link 28, and the spraying device and its positioning mechanism, which is supported by the link 28. Rotating bearings, such as roller bearings or ball bearings, can be used at the rotatable second shafts and the mechanical interconnection of link 28 with second arms 22 and 24. All bearings should be selected to support forces imposed on them by the weight of the spraying machine and spraying device in the most extended position.

The spraying machine may be driven in a number of ways. A rotating power input may be made directly on one of the rotatable first shafts such as that indicated at 29 on rotatable first shaft 12. Rotating power input may be made by means of a sprocket engaging the driving chain, such as indicated at 30, or a reciprocating power input may be made on an extension of one of the first arms, as for example, indicated at 31 acting on an extension of arm 16. The reciprocating power input may be generated by a hydraulic reciprocator. A reciprocating power input can also be obtained from a scotch yoke mechanism operating from a rotating drive.

All of the parts of the spraying machine which move with respect to one another may be joined by rotating bearings. The machine requires no sliding guides which may be contaminated in a spraying operation. Furthermore, link 28 is the only moving member of the spraying machine which would be subjected to forces generated by inaccuracies in manufacture of parts. Such an inaccuracy would, for example, be with respect to the distance between the axes of the first shafts 11 and 12 and the second shafts 19 and 20, between the axes of the second shafts 19 and 20 and the center of the point of connection of second arms 22 and 24 with link 28. Such inaccuracies in distance would result in unequal effective lengths of the first arms and the second arms and thus as link 28 would be reciprocated by the second arms 22 and 24, the effect would be that arms 22 and 24 would attempt to either stretch or compress link 28. The nonuseful forces resulting from the resistance to such stretching and compression imposed upon the spraying machine by rigid link 28 would be transmitted back through the rotating interfaces and tend to bind the machine. The spraying machine of this invention, however, is improved over the spraying machines in the prior art in that only one such rigid link is used, rather than two as in some prior art machines. The effect of any such nonuseful forces can be reduced by making link 28 capable of variation in length by, for example, making it of coaxial, nested 'tubular members.

Link 28 supports by to adjust the position of the spraying device with respect to the spraying machine. Means includes an arm 32 cantilevered with link 28. Arm 32 is pivotally supported to link 28 by shaft 33 and includes an upwardly extending tab 34 connected with the piston 35 of a hydraulic cylinder 36 b means of a clevis 37. The spraying device is mounted on a fitting 38 at the end of arm 32. Fitting 38 is pivotally mounted by shaft 39 to arm 32. Fitting 38 extends below arm 32 and includes a portion 38a connected by means of rod 39 to link 28. Thus, as piston 35 of hydraulic cylinder 36 is extended, arm 32 is lowered, lowering fitting 38 to which the spray device would be attached. Arm 32, rod 39, fitting 38 and link 28 form a parallelogram linkage which maintains the orientation of the spray device on 38 in any preselected attitude with respect to the spraying machine as its position is changed.

A sprocket as referred to in this patent application includes a commercially available sprocket adapted for use with a rotating link chain. However, by sprocket we mean any device capable of being mounted on a rotating shaft and providing a lever arm and means at the end of the lever arm permitting mechanical engagement by a looped inextendible member. A chain, as referred to in this application and as shown in the embodiment of FIGS. 1 and 2, includes a commercially available rotating link chain. However, by chain we mean any inextendible loop member capable of interconnecting two sprocket-like members that provide a lever arm to actuate a rotating shaft.

The illustrated embodiment of this invention is particularly adapted to spraying automobile bodies by supporting a spraying device over the automobile body from the side of the conveyor and reciprocating the spray gun back and forth in a straight line. The spray gun would be oriented to spray downwardly onto the automobile body. By lowering arm 32 of the spraying machine, the spray gun could be kept at a fixed distance with respect to both the top and the rear deck of such automobile bodies.

Contouring movement rather than straight-line motion of the spraying device, may also be obtained by a phase adjustment between the first shafts of the machine and unequal lengths of the second arms. Such an adjustment would, of course, require that link 28 be made capable of variation in length between the points of its connection to the second arms. Other changes from the illustrated embodiment of our invention may be made without departing from the spirit and scope of our invention as set forth in the following claims.

We claim:

1. A spraying machine comprising a support member;

two rotatable first shafts supported by the support member, each rotatable first shaft carrying in fixed position with respect to the shaft a first arm, and a synchronizing sprocket;

two stationary sprockets supported on the axes of the two rotatable first shafts;

two rotatable second shafts, each second shaft rotatably carried by one of the first arms andeach second shaft carrying in fixed position with respect to the second shaft a second arm and a second sprocket;

a link movably carried by the second arms to tie the second arms together and to carry a spraying device;

two chains, each chain interconnecting one of the stationary sprockets and the second sprocket rotatable carried by the first arm on the axis of the stationary sprocket and each chain rotating the first shaft and second shaft simultaneously in opposite directions;

a driving chain interconnecting the synchronizing sprockets;

means to drive the spraying machine by forcing rotation of the synchronizing sprockets whereby the spraying machine converts rotation of the synchronizing sprockets into reciprocating straight-line motion of the link.

2. The spraying machine of claim 1, wherein the means to drive the spraying machine is a motor whose rotating output is connected with the driving chain.

3. The spraying machine of claim 1, wherein the means to drive the spraying machine includes a reciprocating drive connected to one of the arms.

4. The spraying machine of claim 1, wherein the link carries a parallelogram linkage supporting the spraying device and a second means connected with the parallelogram linkage to move the spraying device to different positions with respect to the link.

5. The spraying machine of claim 1, wherein the link is rigid and is capable of extension and contraction.

6. The spraying machine of claim 5, wherein the second arms are of unequal length between the axes of their second shafts and their points of interconnection to the link and the first shafts are not in phase in their rotation whereby a contouring motion is given the spraying device.

" UNlTED STATES PATENT oFFIcE CERTlFlCATE or ECTIN Patent No. 3 a 812 728 Dated y 28 19 74 Inventor) Henry B. Lee et al.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line A l, "centilevered should read cantilevered --v. Column 5, line 22, "by" should read means line 27,

"b" should read by Column 6, lines 30-31, "rotatable" should read rotatably Signed and sealed this 15th day of October l974.

(SEAL) Attest:

MCCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMM-DC 50376-P69 U 5 GOVERNMENT PRINTING OFFICE. 869. 930 

1. A spraying machine comprising a support member; two rotatable first shafts supported by the support member, each rotatable first shaft carrying in fixed position with respect to the shaft a first arm, and a synchronizing sprocket; two stationary sprockets supported on the axes of the two rotatable first shafts; two rotatable second shafts, each second shaft rotatably carried by one of the first arms and each second shaft carrying in fixed position with respect to the second shaft a second arm and a second sprocket; a link movably carried by the second arms to tie the second arms together and to carry a spraying device; two chains, each chain interconnecting one of the stationary sprockets and the second sprocket rotatable carried by the first arm on the axis of the stationary sprocket and each chain rotating the first shaft and second shaft simultaneously in opposite directions; a driving chain interconnecting the synchronizing sprockets; means to drive the spraying machine by forcing rotation of the synchronizing sprockets whereby the spraying macHine converts rotation of the synchronizing sprockets into reciprocating straight-line motion of the link.
 2. The spraying machine of claim 1, wherein the means to drive the spraying machine is a motor whose rotating output is connected with the driving chain.
 3. The spraying machine of claim 1, wherein the means to drive the spraying machine includes a reciprocating drive connected to one of the arms.
 4. The spraying machine of claim 1, wherein the link carries a parallelogram linkage supporting the spraying device and a second means connected with the parallelogram linkage to move the spraying device to different positions with respect to the link.
 5. The spraying machine of claim 1, wherein the link is rigid and is capable of extension and contraction.
 6. The spraying machine of claim 5, wherein the second arms are of unequal length between the axes of their second shafts and their points of interconnection to the link and the first shafts are not in phase in their rotation whereby a contouring motion is given the spraying device. 